P1200: RELAPSE AND OCCURRENCE OF SECOND PRIMARY MALIGNANCIES IN PATIENTS WITH DIFFUSE LARGE B CELL LYMPHOMA IN RITUXIMAB ERA, A NATIONWIDE OBSERVATIONAL STUDY
Authors: H. J. Lee, M. H. Chang, S. V. Anh, D. W. Kim, Y. E. Lee
Journal: HemaSphere (2022)

Background: Diffuse large B cell lymphoma (DLBCL) is the most common type of B cell lymphoma. Rituximab, Cyclophosphamide, Adriamycin, Vincristine, and prednisolone (R-CHOP) is the standard of care in newly diagnosed DLBCL and has been covered by National Health Insurance Service (NHIS) of Korea since October 2004. The Korean government has established the National Health Information Database (NHID) in 2006. NHID contains identified claims, health screening data and mortality data and has been provided to researchers since 2010. Aims: We conducted retrospective study using data from NIHD to describe the type and timing of relapse and occurrence of second primary malignancies (SPM) in patients with DLBLC who were treated with R-CHOP. Methods: All patients who received inpatient care between 2004 and 2013 for an initial diagnosis of DLBLC in NHID were included. Eligible patients with DLBLC in 2004~2013 were identified after excluding potential pre-existing cares of DLBLC (n=9,610). Event Free Survival (EFS) was defined as time from the 1st day of R-CHOP therapy until relapse or progression, unplanned next treatment, or death as a result of any cause. SPM incidences were evaluated in patients who survived more than 1 year after the 1st day of R-CHOP therapy. The patients were followed up until December 2018 to confirm relapse, death, or occurrence of SPM using cox-proportional hazard model. Results: From 2004 to 2013, a total of 9610 patients who had not been previously diagnosed with another type of cancer and received R-CHOP treatment for the first time were identified. The average age of the patients at the time of diagnosis was 57.5 years (standard deviation 15.04), and the male to female ratio was 56.5% and 43.5%, respectively. 11.53% (n=1108) of patients who received R-CHOP chemotherapy also received radiation therapy. During the entire follow-up period, 5-year survival rate of patients treated with R-CHOP chemotherapy was 65% (95% CI, 64.1 – 66.0), and the 5-year Event Free Survival (EFS) rate was 56.5% (95% CI, 55.5 – 57.4) with time showed a continuously decreasing pattern. DLBCL specific relapse free survivals were 83.7% (95% CI, 82.9 – 84.4) at 1 year and 78.4% (95% CI, 77.5 – 79.3) at 2 year. It was confirmed that there were rare DLBLCL specific relapse cases after 2 years of R-CHOP treatment (Figure 1). Among the 7384 patients who survived 1 year or more after completing R-CHOP therapy, SPM occurred in a total of 493 (6.7%) patients. Hematologic malignancy (34.1%, n=168) was the most common type of SPM, followed by stomach cancer in 49 (9.9%) patients, lung cancer in 44 (8.9%) patients, and colon cancer in 31 (6.3%) patients. Image:Summary/Conclusion: The recurrence was uncommon after 2 years in DLBLC patients treated with R-CHOP therapy as the initial treatment. However, the occurrence of SPM was higher than the cancer prevalence of normal population. SPM could be a factor that affect the life expectancy of the long term survivors from DLBCL. Close monitoring for the occurrence of SPM may be necessary in DLBLC survivorship care.